Rep. Mazie Hirono has an overwhelming lead over former Rep. Ed Case in the Democratic primary for Hawaii’s open Senate seat, according to a new poll.

The Hawaii poll, conducted by Ward Research Inc. for the Honolulu Star-Advertiser, found Hirono ahead of Case, 56 percent to 36 percent. The newspaper reported Hirono led union households by 33 points, while Case led 47 percent to 38 percent among independents for the Aug. 11 contest.

In a positive sign for Democrats, who recognize the race could be competitive in November, both Hirono and Case led former Gov. Linda Lingle (R) by 20 points in potential general election matchups.

The Democratic Senatorial Campaign Committee has endorsed Hirono, who also had a wide cash-on-hand lead over Case at the end of December. Hirono reported having $1 million in the bank compared with $283,000 for Case. Lingle reported more than $1.4 million in cash on hand.

The live telephone poll was conducted Jan. 26 to Feb. 5. It included interviews with 599 registered voters for the primary with a 4-point margin of error and 771 registered voters for the general with a 3.5-point margin of error.

Roll Call rates the general election contest as Leans Democratic.